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Exchange 2016 OWA will not open in Firefox or Chrome.

Question

Just upgraded from Exchange 2010 to Exchange 2016, now OWA in Exchange 2016 will not open in Firefox or Chrome, it will open in IE and Microsoft Edge.

Here is the error I get in FireFox:

Your connection is not secure

The website tried to negotiate an inadequate level of security.

my.domain.com uses security technology that is outdated and vulnerable to attack. An attacker could easily reveal information which you thought to be safe. The website administrator will need to fix the server
first before you can visit the site.

Error code: NS_ERROR_NET_INADEQUATE_SECURITY

I have google this for 2 days now and have double check all SSL certs, permission settings etc, and I don't know how to fix this, if anyone has any ideas I would love to hear them. Thanks John

Tears to my eyes!!! I can't believe how well and fast this worked.. I knew it had to do with TLS & HTTP2, but I was working it from a web browser angle,, this tool fixed it at the IIS level for everybody...

HOWEVER when the server rebooted, the network had gained an exclamation mark "no internet access". Ran the Diagnostics, which reset the TCP/IP stack, rebooted, had gone back to DHCP. Set back to static IP and all OK now.

It's the third party browsers. Their "Shellshock" and "Heartbleed" SSL encryption bug "repair" was just to blacklist the encryption levels they couldn't handle. Those vulnerabilities never affected Microsoft, so there's nothing
to fix on the Microsoft side!

The "fix" is to either remove the capability or reorganize the crypto on your Windows servers to not offer those higher levels to those browsers.

The problem is so many of those browsers are also used in phones, so good luck trying to get ActiveSync working if your server is public facing! You could put a KEMP load balancer or something of the sort in front to mitigate the issue, but there you go!

By the way, this also applies to SharePoint, or any other server you try to use a Nix based browser on.

I know, it's called putting your head in the sand, and calling it "fixed"! GRRRRR